This invention describes a method for micro-encapsulating a volatile liquid in a porous particle. A preselected porous particle of known weight and porosity is blended with the volatile liquid to be encapsulated, the quantity of volatile liquid being insufficient to fill all of the void spaces in each particle. The blended mixture is placed under vacuum which draws the liquid into the center of each particle. This partially filled particle is referred to hereafter as Part A. An additional volume of the volatile liquid is blended with a polymer resin catalyst (i.e. epoxy or polyurethane) at a predetermined ratio. This blend of polymer resin catalyst and volatile liquid is referred to hereafter as Part B.
Part A is blended with a specific volume of Part B, said volume is calculated to bring the total amount of liquid inside the porous particle to saturation. This blend of Part A and Part B is saturated and may be placed under vacuum to assure saturation of the particles. This saturated particle is referred to herein as Part C.
Part C is blended with a preselected polymer resin capable of being cured with the polymer catalyst in part B. The polymer resin, when cured with the polymer resin catalyst in Part B, is chemically stable in the volatile liquid. When the Part C resin comes into contact with the surface of the porous particle containing Parts B, the resin in contact with the surface of each particle cures to form a hardened, rigid, chemical resistant, polymer shell around each particle.
The result is hardened, frangible, chemically resistant, microcapsules of volatile liquid.
The preferred composition includes 40-50%, porous particles, 40-50% isophorone, 2-6% polymer catalyst, and 5-15% polymer resin.
A specific formula is:
Part A: 45% porous particle; 34% isophorone.
Part B: 11% Isophorone; 0.5% polymer catalyst
Part C: 9% polymer resin.
The preferred volatile liquid is isophorone (3,5,5-trimethyl-2-cyclohen-one-1) obtained from Union Carbide. A preferred porous particle is Veri-lite (ceramic refractory material in round beads) obtained from Harbison Walker Refractories Company but other porous particles, such as wood pulp, can also be used. The polymer catalyst is IFOAM Catalyst obtained from ICORP-IFOAM Specialty Products Corporation (as seen in my prior U.S. Pat. Nos. 4,092,296 and 4,773,792). The polymer resin is Bisphenol A Diglycidal Ether obtained from Shell Chemical under their formulation Epon 828.
A process of micro-encapsulating a volatile liquid includes selecting a volatile liquid, such as Isophorone, and porous ceramic particles for encapsulating the volatile liquid. The volatile liquid and porous particles are mixed and a vacuum is applied to the mixture to impregnate the volatile liquid in the porous particles. A polymer catalyst for the polymer resin, such as an epoxy catalyst for use with an epoxy resin, is mixed with the volatile liquid and porous particles to saturate the particles. The polymer resin, such as epoxy resin, is added to the mixture for forming a resin cured shell around the porous particle holding the volatile liquid to form a microencapsulated volatile liquid. The resin is only cured on the outer shell of the porous particle when coming in contact with the catalyst supported with the volatile liquid in the porous particle.